This
page
is
part
of
the
FHIR
Specification
(v3.3.0:
(v3.5.0:
R4
Ballot
2).
#2).
The
current
version
which
supercedes
this
version
is
5.0.0
.
For
a
full
list
of
available
versions,
see
the
Directory
of
published
versions
.
Page
versions:
R5
R4B
R4
R3
FHIR
Infrastructure
Work
Group
|
Maturity Level : 5 | Ballot Status : Normative |
Normative Candidate Note: This page is candidate normative content for R4 in the Infrastructure Package . Once normative, it will lose it's Maturity Level, and breaking changes will no longer be made.
This page documents the way version change is handled in FHIR. FHIR is a standard, so the way version change is handled is a bit different from an application API. This page describes:
See also Managing FHIR Versions for additional implementer advice about dealing with versions.
FHIR is a standard. In order to be useful, standards need to evolve. At the same time, the evolution of standards needs to be predictable and manageable for the implementation community. This section describes how HL7 develops a standard so that implementers know what to expect as the standard evolves.
HL7 has four descriptive terms that describe the level of stability and implementation readiness associated with different aspects of the specification. They are as follows:
| Standard Level | Description |
|---|---|
| Draft | This portion of the specification is not considered to be complete enough or sufficiently reviewed to be safe for implementation. It may have known issues or still be in the "in development" stage. It is included in the publication as a place-holder, to solicit feedback from the implementation community and/or to give implementers some insight as to functionality likely to be included in future versions of the specification. Content at this level should only be implemented by the brave or desperate and is very much "use at your own risk". The content that is Draft that will usually be elevated to Trial Use once review and correction is complete after it has been subjected to ballot |
| Trial Use |
This content has been well reviewed and is considered by the authors to be ready for use in production systems. It has been subjected to ballot and approved as an official standard. However, it has not yet seen widespread use in production across the full spectrum of environments it is intended to be used in. In some cases, there may be documented known issues that require implementation experience to determine appropriate resolutions for. Future versions of FHIR may make significant changes to Trial Use content that are not compatible with previously published content. |
| Normative | This content has been subject to review and production implementation in a wide variety of environments. The content is considered to be stable and has been 'locked', subjecting it to FHIR Inter-version Compatibility Rules . While changes are possible, they are expected to be infrequent and are tightly constrained. |
| Informative | This portion of the specification is provided for implementer assistance, and does not make rules that implementers are required to follow. Typical examples of this content in the FHIR specification are tables of contents, registries, examples, and implementer advice |
| Deprecated | This portion of the specification is provided for implementer assistance, and does not make rules that implementers are required to follow. Typical examples of this content in the FHIR specification are tables of contents, registries, examples, and implementer advice |
Some Normative artefacts contain a few parts labeled as 'Trial Use' even though the artrfact itself is labeled 'Normative' :
While HL7 prefers to avoid this outcome, there are a number of resources where the overall functionality of the artefact is clearly ready to be labeled as 'normative' while some very specific parts are known not to have the requisite level of implementation experience as the rest of the resource. E.g. Bundle.signature .
Where a Normative resource contains elements marked as trial-use, these elements are clearly marked in the resource definitions. Implementers should be aware that future versions of the FHIR specification may change these parts of the resources (in addition to the other changes allowed under the inter-version compatibility rules . While HL7 will carefully consider the consequences of breaking change to these elements, implementers should be aware that reading/using these elements has the potential to cause breaking change to their applications later.
Note that this same status will arise as a matter of process when new elements are introduced into normative resources in future versions - they will undergo a period of trial use as appropriate.
Note: it is also possible that some resources in the future will be labeled as 'trial use', but contain some elements labeled as 'normative'. There is no resource like this in this specification, though all Trial Use resources contain normative content from Resource and DomainResource , and the Data types .
This release (Release 3) is an Trial Use Specification, though a little of the content (where marked specifically at the top of the page) is Draft . For Release 4, some content is planned to be Normative .
Notes:
The
content
of
this
release
has
been
subject
to
significant
review
through
ballot
and
other
HL7
processes
and
many
aspects
of
it
have
been
implemented
and
subjected
to
interoperability
testing
through
Connectathons
and
early
adoption.
However,
the
degree
of
testing
has
varied.
Some
resources
have
been
well
tested
in
a
variety
of
environments.
Others
have
received
relatively
little
real-world
exercise.
In
general,
the
infrastructure
should
be
considered
to
be
more
stable
than
the
resources
themselves.
In
some
cases,
there
are
issues
on
which
input
is
specifically
requested
during
the
Trial
Use
period
(see
the
Outstanding
Issue
List
,
and
known
issues
will
arise
after
publication
(refer
to
the
FHIR
Change
Request
tracker
for
details.)
Guidance
from
early
implementation
will
help
address
these
areas.
All
artifacts
in
this
specification
are
assigned
a
"Maturity
Level",
known
as
FMM
(after
the
well
known
CMM
grades).
The
FMM
level
can
be
used
by
implementers
to
judge
how
advanced
-
and
therefore
stable
-
an
artifact
is.
The
following
FMM
levels
are
defined:
| Draft (0) |
the
resource
or
profile
(artifact)
has
been
published
on
the
current
build.
This
level
is
synonymous
with
Draft
|
| FMM 1 |
PLUS
the
artifact
produces
no
warnings
during
the
build
process
and
the
responsible
WG
has
indicated
that
they
consider
the
artifact
substantially
complete
and
ready
for
implementation.
For
resources,
profiles
and
implementation
guides,
the
FHIR
Management
Group
has
approved
the
underlying
resource/profile/IG
|
| FMM 2 |
PLUS
the
artifact
has
been
tested
and
successfully
|
| FMM 3 |
PLUS
+
the
artifact
has
been
verified
by
the
work
group
as
meeting
the
|
| FMM 4 |
PLUS
the
artifact
has
been
tested
across
its
scope
(see
below),
published
in
a
formal
publication
(e.g.
Trial-Use
),
and
implemented
in
multiple
prototype
projects.
As
well,
the
responsible
work
group
agrees
the
|
| FMM 5 |
the
artifact
has
been
published
in
two
formal
publication
release
cycles
at
FMM1+
(i.e.
|
|
Normative
|
the artifact is now considered stable |
Tested across scope means:
has
signed
off
on
the
list
of
"example
contexts"
defined
for
the
artifact
The
Maturity
level
is
strongly
related
to
stability;
the
higher
the
maturity
level,
the
more
controls
are
enforced
to
restrict
breaking
changes
to
the
resource.
For
further
information,
and
discussion,
see
the
FHIR
Wiki
.
The
maturity
model
is
significantly
influenced
by
the
degree
and
type
of
implementation
activity
using
an
artifact.
For
this
reason,
we
encourage
implementers
to
register
their
implementations
.
A
detailed
analysis
of
the
basis
for
the
maturity
metrics
for
FHIR
artifacts
can
be
found
here
.
New
versions
of
FHIR
will
be
published
on
a
release
cycle
of
approximately
18-24
months.
This
frequency
is
based
on
the
timelines
necessary
to
consult
with
implementers,
to
develop
and
develop,
review
new
content
content,
as
well
as
to
undertake
the
formal
balloting
and
reconciliation
processes
required
for
ANSI-approved
standards.
This
release
cycle
also
ensures
an
opportunity
to
incorporate
implementer
feedback
from
earlier
versions
of
the
specification
into
subsequent
versions.
Limited-scope
releases
on
a
shorter
timeline
may
occur
occasionally
where
necessary
to
meet
implementer
desires.
needs.
Each
new
release
is
assigned
a
unique
version
number.
The
FHIR
version
policy
is
based
on
Semantic
versioning
,
but
with
some
differences
due
to
the
fact
that
FHIR
is
a
specification,
not
a
software
API.
There is a single development version of FHIR. This undergoes cycles of development as managed by HL7. Each major cycle of development is concluded by a formal ballot (or more than one), and then a new specification is published. In version control terms, each published specification is a branch off the development trunk, which may then itself undergo further change as HL7 maintains the published specification (though such changes are usually minimal, limited to necessary technical corrections or security alerts).
Each FHIR version is identified by a string composed from 4 parts: publication.major.minor.revision.
| publication |
|
| major |
|
| minor |
|
| revision |
|
Additional notes:
)
-
does
not
conform
to
this
version
policy,
in
that
the
version
is
not
updated
as
changes
are
made.
To
indicate
this,
the
revision
is
always
"cb"
e.g.
3.1.cb
immediately
after
the
publication
of
Release
3
There is no explicit version marker in the content of FHIR resource instances. Instead, the version supported by a given system is declared using the conformance framework . The resources CapabilityStatement and StructureDefinition have properties for declaring the FHIR specification version, and these may be used to determine which version of FHIR an implementation is using to aid in validation and integration.
The following kinds of changes may be made to the specification:
Note
that
the
following
are,
by
definition,
considered
non-breaking
changes,
even
though
some
implementations
(including
the
reference
implementations)
might
not
be
able
to
handle
some
consequences
of
these
changes
without
error:
Creation
of
new
resources
Adding
new
optional
elements
in
an
existing
resource
Defining
new
data
types
Adding
new
API
operations
NOTE:
The
examples
provided
as
part
of
this
specification
are
never
substantive.
While
every
effort
is
made
to
ensure
that
FHIR
examples
are
correct,
changes
to
the
examples
in
the
specification
are
not
considered
substantive.
Content with a status of Draft or Trial Use can change - including Breaking Changes - from version to version, subject to the rules described by the Maturity Process . There are no rules for maintaining any sort of compatibility between versions for content with these statuses, though of we will only make breaking changes based on feedback from the community.
Once
an
artifact
achieves
Normative
status,
the
Backward
compatible
behavior
specific
rules
will
apply.
come
into
play
around
inter-version
compatibility.
These
rules
ensure
that
implementations
may
have
implication
for
both
forward
and
backward
compatibility
and
are
intended
to
allow
implmeentations
to
exercise
FHIR
interfaces
and
process
the
content
of
FHIR
resources
safely
while
exchanging
data
between
applications
systems
using
different
versions
of
FHIR.
There
Forward
compatibility
means
that
content
that
is
no
explicit
version
marker
conformant
in
an
old
release
will
remain
conformant
with
future
versions.
Once
normative,
FHIR's
rules
try
to
enforce
forward
compatibility.
However,
that
doesn't
guarantee
that
all
old
systems
will
interoperate
with
future
systems.
Backward
compatibility
means
that
instances
created
against
future
versions
of
the
content
specification
will
interoperate
with
older
versions
of
FHIR
resource
instances.
Instead,
the
version
supported
by
a
given
system
specification.
This
is
declared
using
the
conformance
framework
.
The
resources
CapabilityStatement
and
StructureDefinition
have
properties
for
declaring
the
FHIR
specification
version,
and
these
may
be
used
not
guaranteed
by
FHIR,
though
there
are
strategies
systems
can
adhere
to
determine
which
version
that
will
increase
their
chances
of
FHIR
such
interoperability.
Specifically,
when
dealing
with
content
from
a
system
supporting
an
implementation
is
using
to
aid
in
validation
unknown
normative
version
and
integration.
2.7.0.4.2
Forward
compatible
behavior
In
a
typical
scenario,
mixed
versions
may
need
wishing
to
exist,
so
maximize
backwards
compatibility,
applications
SHOULD
ignore
SHOULD:
However,
in
a
healthcare
context,
many
application
vendors
implementers
are
unwilling
to
consider
this
approach
some
of
these
steps
because
of
concerns
about
clinical
risk
or
technical
limitations
in
their
software
(e.g.
schema
based
processing).
Applications
are
not
required
to
ignore
unknown
elements,
but
SHALL
declare
whether
they
will
do
so
in
their
Capability
Statements
.
Unrecognized
search
criteria
SHOULD
always
be
ignored
-
see
Handling
Search
Errors
for
further
information.
Attempts
to
perform
HTTP
operations
on
unexpected
URLs
SHOULD
be
responded
to
with
an
appropriate
error
code.
| Category | Allowed changes |
|---|---|
|
|
|
| Artifacts (resources, profiles, code systems, etc.) | New artifacts including new resources and data types may be introduced. Existing artifacts will not have any computable identifiers (e.g. resource names) changed. Artifacts may be deprecated |
| Elements |
New
optional
elements
and/or
content
(e.g.
XML
attributes,
etc.)
at
any
location
in
|
| Cardinality | Minimum element cardinalities will not be changed. Upper cardinality may change from 1 to * only in circumstances where all elements except for the first repetition can be safely ignored. (This may mean that an order is assigned to the repeating items or that there is no preference as to which element is retained.) Systems should follow the rules above for unexpected elements. |
| Descriptions | Descriptive information about a resource - short labels, definitions, usage notes, aliases, examples, rationale, mappings, etc. may be updated or revised to provide additional clarity or guidance, but not in such a manner as to invalidate a reasonable interpretation of the previously documented use of an element. (This does not preclude fixing obvious errors.) |
| Value Sets |
The definition of any value set that is marked as immutable will never change. The expansions for immutable value sets may still change if no "stable date" is declared and the value set does not restrict code system and/or value set references to specific versions and the codes in the referenced code system(s) or value set(s) change. For non-immutable value sets:
For both immutable and non-immutable value sets, additional designations may be declared. Normative CodeSystems whose content is generated from a mix of normative and non-normative contents may break these rules. For example, the code system containing the list of all resources may have codes removed or renamed as non-normative resources are removed or renamed. |
| Terminology Bindings |
|
| Data Types |
Data
types
will
not
be
removed
or
changed
except
as
allowed
above
for
elements.
New
data
types
may
be
introduced.
Types
declared
on
existing
elements
will
not
be
removed
or
string
may
be
changed
to
markdown
.
Additional
data
types
may
be
added
to
elements
which
are
already
expressed
as
a
choice
of
data
types
only
if
those
elements
are
optional
(minimum
cardinality
=
0).
|
| Value Constraints | The allowed list of Data types will not be added, removed or changed. Invariants, regular expressions, fixed values and patterns will not be added, removed or changed. |
| Flags | The Is Modifier and Is Summary flags will not be changed. |
| Slicing | Slicing rules and aggregation characteristics will not be changed. |
| Search Criteria | Search criteria may be added but not removed or renamed. Existing criteria will not have their type or path changed or have their description altered in any way that would invalidate the reasonable behavior of existing systems (with the exception of correcting obvious errors). |
| Operations |
New
operations
may
be
defined
but
operations
|
| Restful interface | Existing endpoints will not be renamed or removed, nor have their expected behavior changed in a manner that would cause reasonable systems designed against prior versions to be non-interoperable. Additional endpoints and interactions may be introduced. |
| Profiles and extension definitions | Profile structure, extension definitions and search criteria definitions will not be removed or have their URIs changed. New profile structures, extension definitions and search criteria definitions may be introduced. Profiles may have their statuses changed to "retired". Profiles referenced by data elements for structures or data types may be replaced with a reference to a distinct profile that is "compatible" with the previously referenced profile according to these forward and backward compatibility rules. |
| Capability Statements | Within the CapabilityStatements for defined FHIR Services or 'core' implementation guides, additional operations may be added. These additions might be optional (MAY/SHOULD) or mandatory (SHALL). Note that the introduction of mandatory operations would break forwards compatibility and will only occur with community consultation. |
| Implementation Guides | Additional artifacts can be added and artifacts can be changed. The list of global profiles will not change |
| References | Where one conformance resource points to another (e.g. CapabilityStatement to profile, profile to profiles, profile to value set, etc.), the reference may change to point to a newer version of the conformance resource or to a distinct conformance resource so long as the content of the newly referenced resource adheres to the compatibility rules with respect to the previously referenced version. |
NOTE: In rare circumstances, HL7 may approve changes that technically break one of the above rules in situations where there is a high level of confidence that the change will not impact existing implementers. Such deviations from these declared rules will involve broad notification, extensive community consultation and reviews by multiple levels of HL7 governance processes.
Once
content
is
normative,
there
is
a
process
for
removing
it
from
the
standard
by
marking
it
as
deprecated
or
withdrawn
(from
the
HTML
4.0
Standard
):
| Deprecated | Systems should continue to support the artefact/feature/concept, but are discouraged from making use of it |
| Withdrawn | Documented for historical purposes, no longer supported |
The
specification
will
provide
guidance
with
deprecated
materials
showing
how
to
avoid
using
them.
Deprecated
materials
are
eligible
to
be
balloted
to
be
withdrawn
two
years
after
their
deprecated
status
is
published.
The computable artifact labels (e.g. codes, element names, urls, etc) associated with withdrawn materials SHALL not be used in future versions of HL7 specifications. Materials marked "deprecated" may have that marking removed as part of a subsequent ballot at a later moment, while withdrawn materials SHALL NOT.
The following artefacts are deprecated in this version of FHIR:
Additional
discussion
on
inter-versioning
issues
can
be
found
here:
http://wiki.hl7.org/index.php?title=FHIR_interversion_compatibility
.
Regardless
of
the
degree
of
prior
implementation,
all
aspects
of
the
FHIR
specification
are
potentially
subject
to
change
while
an
artifact
has
a
status
of
Draft
or
Trial
Use
.
These
changes
may
be
minor
(clarifications
of
definitions,
etc.)
or
major
(refactoring
of
resources,
changes
to
serialization
rules,
eliminating
or
adding
data
types,
etc.)
There
is
no
commitment
to
backward
or
forward
compatibility
during
the
STU
process.
trial
use
process
until
content
is
normative.
Changes
will
not
be
made
without
cause,
however
the
interests
of
long-term
implementability
will
generally
trump
the
impact
on
early
adopters
when
determining
what
changes
should
be
made.
This
balance
will
shift
more
towards
early
adopters
as
maturity
levels
increase.
I.e.
Impact
on
existing
implementations
will
be
weighted
more
highly
for
an
FMM-level
5
artifact
than
they
would
for
an
FMM-level
1
artifact.
Implementers who are willing to accept the risk of change (perhaps for the benefit of early implementation experience, first mover advantage and the ability to leverage FHIR's intrinsic benefits) are encouraged to implement those parts of FHIR that are early in the maturity cycle in real-world systems. However, those implementers should be aware that local adaptations may be necessary to meet real-world requirements. Furthermore, such implementers should architect their solutions to be tolerant of changes to the specification and, where necessary, to manage interoperability with systems that may be using different versions of the specification or different local adaptations.
The
most
common
strategy
for
handling
change
between
versions
of
FHIR
is
to
use
different
end-points
for
different
versions.
e.g.
http://acme.com/fhir/r2
and
http://acme.com/fhir/r3,
though
other
approaches
are
possible.
During
the
Trial
Use
period,
requests
for
change
may
be
submitted
using
the
HL7
gForge
tracker
which
can
be
found
here
.
Where
possible,
updates
to
the
"development"
version
of
the
specification
will
be
made
in
a
timely
fashion.
Implementers
should
be
aware
that
the
changes
are
not
considered
"official"
until
such
time
as
they
are
balloted
and
approved
as
part
of
a
subsequent
Trial
Use
or
Normative
publication.
Change
requests
might
be
fixes
to
allow
implementation,
clarifications
or
enhancements.
In
addition,
HL7
will
be
developing
and
introducing
additional
resources
and
profiles
as
part
of
the
FHIR
specification.
SDOs and regulatory bodies that are interested in making use of the FHIR specification should feel free to do so, but should consider and plan for the possibility that the specification will evolve and change prior to becoming Normative .
A
key
objective
aspeect
of
the
Trial
Use
FHIR
specification
development
process
is
gaining
feedback
from
implementers
making
use
of
the
specification.
As
well,
HL7
has
a
need
to
monitor
which
portions
of
FHIR
are
being
implemented
in
what
sorts
of
environments
so
as
to
make
an
informed
decision
on
when
the
specification
process
is
ready
to
proceed
conditional
on
real
world
implementation
in
order
to
Normative
status.
move
through
the
maturity
cycle.
For
this
reason,
all
FHIR
implementers
are
encouraged
to
register
their
usage
here
.
This
survey
will
capture
,
which
captures
contact
and
other
information
that
will
allow
the
FMG
HL7
to
perform
appropriate
monitoring
of
FHIR
STU
usage.
Survey
information
will
be
kept
is
confidential
unless
and
reported
in
aggregate
only.
Many
implementations
need
to
convert
resources
from
one
FHIR
version
to
another.
Once
resources
become
normative
(once
sufficiently
mature
and
stable),
converting
resources
forwards
from
past
versions
is
not
needed.
Converting
back
to
older
versions
presents
a
challenge,
however,
in
that
the
participant
authorizes
inclusion
newer
version
may
add
additional
elements
that
are
not
present
in
the
older
version.
In
some
cases,
the
elements
are
simply
irrelevant
since
the
requirements
they
represent
are
not
in
scope
for
older
applications,
but
in
other
cases,
it
is
necessary
to
represent
the
data
in
order
to
cater
for
round-tripping.
A
more
complex
problem
arises
with
resources
that
are
not
yet
stable
(early
in
the
maturity
process).
If
applications
have
implemented
less
stable
resources,
not
only
do
they
have
the
problem
of
their
project
new
elements
for
new
requirements,
the
specification
may
change
in
either
compatible
or
incompatible
ways,
and
it
may
be
necessary
to
carry
data
elements
from
past
versions
forward
in
order
to
allow
seamless
round-tripping.
In
order
to
help
implementers
with
this
problem,
any
element
defined
in
any
version
of
FHIR
is
automatically
assigned
an
HL7-maintained
wiki
page
extension
URL
that
uniquely
identifies
the
element
and
can
be
used
in
the
relevant
FHIR
version.
The
extension
URL
for
an
element
can
automatically
be
derived:
http://hl7.org/fhir/[version]/StructureDefinition/extension-[Path]
where [version] is taken from this list:
This
technique
can
be
used
with
all
versions
of
early
implementers.
Confidential
submissions
will
FHIR,
including
R2
and
R3:
FHIR
DSTU2
![]() | 1.0 |
FHIR
R3
(STU3,
or
just
R3)
| 3.0 |
FHIR
R4
(this
version)
| 4.0 (once published) |
Note that this extension framework only applies back to DSTU2. The [Path] is actually the ElementDefinition.id from the relevent StructureDefinition for the element. This leads to URLS like the following:
http://hl7.org/fhir/4.0/StructureDefinition/extension-Bundle.signature
|
R4
Signature
Element
on
Bundle
![]() |
http://hl7.org/fhir/3.0/StructureDefinition/extension-Patient.animal.species
|
STU3
Species
Element
on
Patient
![]() |
http://hl7.org/fhir/1.0/StructureDefinition/extension-ValueSet.extensible
|
DSTU2
ValueSet.extensible
![]() |
Implementers
should
be
reported
aware
of
the
following
issues
when
using
these
extensions:
This table shows the mapping between primitive data types across versions:
| R4 | R3 | DSTU2 |
| base64Binary | base64Binary | base64Binary |
| boolean | boolean | boolean |
| canonical | (uri) | (uri) |
| code | code | code |
| date | date | date |
| dateTime | dateTime | dateTime |
| decimal | decimal | decimal |
| id | id | id |
| instant | instant | instant |
| integer | integer | integer |
| markdown | markdown | markdown |
| oid | oid | oid |
| positiveInt | positiveInt | positiveInt |
| string | string | string |
| time | time | time |
| unsignedInt | unsignedInt | unsignedInt |
| uri | uri | uri |
| url | (uri) | (uri) |
| uuid | uuid | (id) |
Formal Definitions for extensions:
Note for balloters: these packages will be created when R4 is finalized. Until then, these are broken links.
While
implementation
of
this
Trial
Use
release
is
occurring,
development
will
be
progressing
on
the
next
release.
This
next
release
will
include
additional
resources,
profiles
and
quality
enhancements
over
the
current
release.
It
will
also
incorporate
fixes
for
issues
raised
with
the
FHIR
change
tracker
.
It
may
be
useful
for
implementers
of
the
STU
to
review
the
development
release
to
get
a
sense
of
what
changes
are
likely
coming
and
perhaps
to
find
more
robust
definitions
and
guidance
than
are
available
in
the
first
release.
The
FHIR
development
release
can
be
found
at
build.fhir.org
.
Some
implementers
who
are
dependent
on
content
that
exists
in
a
draft
release
may
choose
to
implement
based
on
a
particular
snapshot
of
the
development
release,
though
in
doing
so,
they
will
limit
their
potential
communication
partners
and
would
not
be
considered
to
be
completely
FHIR
conformant.
The next major publication of FHIR will be Release 4. It is our hope that this release will include the transition of some of the content of the specification to Normative . This should include many of the core infrastructure resources (e.g. StructureDefinition , ValueSet as well key pages such as the XML and JSON syntaxes, RESTful protocol, etc. It should also include at least a few of the administrative resources such as Patient . Much content, including most if not all clinical and business resources, will remain at the Trial Use level as they are not expected to meet the criteria for Normative.
The
anticipated
timeline
for
Release
4
involves
a
finalization
of
scope
by
the
end
of
2017,
balloting
in
April
of
2018
and
publication
around
October
2018.
The
specific
timing
may
vary
based
on
implementer
feedback
and
the
volume
of
contents
received
during
the
ballot
process.
More
information
on
plans
for
Release
4
can
be
found
on
the
HL7
product
director's
blog
.
(Subscribing
to
this
blog
is
a
good
way
to
keep
current
on
significant
events
in
FHIR
development,
including
ballot
and
publication
timelines.)
There will be additional releases of FHIR with a frequency of between 18 and 24 months for the foreseeable future. These releases will include new content (e.g. in the public health, financial or clinical research spaces), revisions reflecting implementer feedback and increasing maturity on Trial Use artifacts and the migration of additional content to normative status. As well, HL7 will gradually shift focus to providing additional guidance through the publication of implementation guides and profiles where consensus can be found at the international level.